Mesmo Brings Cardano Functions to Four Programming Languages

Cardano Foundation introduced Mesmo on September 24 to give developers another way to work with Cardano features outside Java. It packages selected functions from Cardano Client Lib into a native shared library that applications can call without running a Java Virtual Machine.

Mesmo Works Alongside Existing SDKs

Developers already build Cardano applications with tools such as pycardano, MeshJS, Lucid and Pallas. Each SDK has its own release cycle, so support for a new protocol function may arrive at different times. Mesmo lets a team use selected Cardano Client Lib functions while continuing to rely on its usual SDK for the rest of the application.

The project uses GraalVM Native Image to compile the Java library into a native binary with a standard C interface. Language wrappers expose its functions to Python, Go, Rust and JavaScript. Developers can therefore use those operations across different environments without maintaining a Java service.

Building Transactions Without Running a Node

Mesmo covers account and address handling, cryptography, transaction construction and signing. Its transaction model includes payments, staking, DRep registration, governance votes, native scripts and Plutus scripts. The library also provides Plutus datum hashing and offline execution costing.

For example, a team whose primary SDK does not yet support a particular governance action could use Mesmo to build and sign that transaction. The application would still obtain current blockchain data through a separate provider and submit the finished transaction through its existing infrastructure.

Mesmo itself does not synchronize the chain or maintain a node connection.

Cardano Foundation says automated tests build and submit supported transaction types from each language wrapper to a development network. The tests also check that the node rejects invalid transactions. This checks the resulting transactions against network rules, beyond confirming that the wrappers can call the library.

Pre-Release Limits and Next Steps

Mesmo remains a pre-release, and its APIs may change. The native library adds approximately 60 MB to an application. JavaScript support currently uses Bun; Node.js is not supported because of an incompatibility with the current native interface setup.

The roadmap includes additional data-provider integrations and a WebAssembly target. The team plans to move toward beta after the relevant Cardano Client Lib release becomes stable.